This invention relates to an apparatus for nuclear reactors, particularly to an apparatus for the acceleration and deceleration of the movement of a neutron absorbing control element of a nuclear reactor during its scram stroke.
In many types of nuclear reactors the output and uniform fuel consumption of the reactors is controlled by inserting rods bearing a neutron absorbing material thereon into the reactor core. Shutdown or scram may be effected by releasing the control rods, and permitting them to fall with the force of gravity into the reactor core.
In an emergency the control rods must enter into the reactor core sufficiently rapidly to effect an immediate power shut off, and the movement of the control rods must be slowed and stopped at the end of their strokes to prevent damage to the rods and to the core. Prior art methods such as those disclosed in U.S. Pat. No. 3,980,519, issued Sept. 14, 1976, to Taft, and U.S. Pat. No. 4,487,739 issued Dec. 11, 1984, to Thatcher et.al. have been devised to damp the motion of the free falling control rods prior to the point of impact.
It is an object of this invention to provide a reliable and fast acting system for the insertion of control rods into a reactor core including both propulsion and damping of control rod movement.
In the accomplishment of the foregoing object, it is another important object of this invention to provide a method for determining the accelerating pressure required to cause rapid insertion of a control rod as well as the decelerating pressure required to prevent damage to the control rod mechanism.
It is another important object of this invention to provide a method for determining the rate at which decelerating pressure should be relieved to permit the control rod to move through a full stroke and come to rest safely without bouncing.
It is a further object of this invention to present an improvement to a nuclear reactor control rod assembly which controls the movement of the control element throughout the scram stroke.
Additional objects, advantages and novel features of the invention will become apparent to those skilled in the art upon examination of the following and by practice of the invention.